The present invention relates to heat-curable aqueous compositions comprising a carboxyl-containing polymer component and a hydroxyalkylated amine and to their use as binders for shaped articles.
The solidification or consolidation of sheetlike fiber structures such as fiber nonwovens, shaped articles such as fiberboard or chipboard panels, etc., is frequently done chemically using a polymeric binder. To increase the strength, especially the wet strength and heat stability, it is common to employ binders whose crosslinkers give off formaldehyde. However, this brings with it the risk of formaldehyde emissions.
In order to avoid formaldehyde emissions numerous alternatives have already been proposed to the binders known to date. For instance, U.S. Pat. No. 4,076,917 discloses binders whose crosslinkers comprise xcex2-hydroxyalkylamides and polymers which contain carboxylic acid or carboxylic anhydride. The molar ratio of carboxyls to hydroxyls is preferably 1:1. A disadvantage is the relatively complex preparation of the xcex2-hydroxyalkylamide.
EP-A-445 578 discloses sheets made of finely divided materials, such as glass fibers, in which mixtures of high molecular mass polycarboxylic acids and polyhydric alcohols, alkanolamines or polyfunctional amines act as binders. High molecular mass polycarboxylic acids described are polyacrylic acid and methyl methacrylate-n-butylacrylate-methacrylic acid and methyl methacrylate-methacrylic acid copolymers. Polyhydric alcohols or alkanolamines employed are 2-hydroxymethyl-1,4-butanediol, trimethylolpropane, glycerol, poly(methyl methacrylate-co-hydroxypropyl acrylate), diethanolamine and triethanolamine. However, the water resistance of the resulting sheets is unsatisfactory.
EP-A-583 086 discloses formaldehyde-free aqueous binders for producing fiber webs, especially glass fiber webs. The binders comprise a polycarboxylic acid having at least two carboxyl groups with or without anhydride groups. Polyacrylic acid, in particular, is used. The binder also comprises a polyol, for example glycerol, bis[N,N-di(xcex2-hydroxyethyl)adipamide, pentaerythritol, diethylene glycol, ethylene glycol, gluconic acid, xcex2-D-lactose, sucrose, polyvinyl alcohol, diisopropanolamine, 2-(2-aminoethylamino)ethanol, triethanolamine, tris(hydroxymethylamino)methane and diethanolamine. These binders require a phosphorus-containing reaction accelerator in order to achieve sufficient strengths of the glass fiber nonwovens. It is mentioned that a reaction accelerator of this kind can only be absent if a high reactive polyol is employed. xcex2-Hydroxyalkylamides are mentioned as highly reactive polyols.
EP-A-651 088 describes corresponding binders for cellulose fiber substrates. These binders necessarily include a phosphorus-containing reaction accelerator.
EP-A-672 920 describes formaldehyde-free binders, impregnating compositions or coating compositions which comprise at least one polyol and a polymer of which from 2 to 100% by weight is accounted for by an ethylenically unsaturated acid or an acid anhydride comonomer. The polyols are substituted triazine, triazinetrione, benzene or cyclohexyl derivatives, the polyol radicals always being in position 1, 3 and 5 of these rings. Despite a high drying temperature, the wet tear strengths achieved with these binders on glass fiber nonwovens are low. In comparative experiments, amine-containing crosslinkers and predominantly linear polyols were tested as well. It is mentioned that amine-containing crosslinkers have a flocculating effect and that the predominantly linear polyols lead to weaker crosslinking than the cyclic polyols.
DE-A-22 14 450 describes a copolymer composed of from 80 to 99% by weight of ethylene and from 1 to 20% by weight of maleic anhydride. Together with a crosslinker, the copolymer is used, in powder form or in dispersion in an aqueous medium, for surface coating. The crosslinker used is an amino-containing polyalcohol. However, in order to bring about crosslinking it is necessary to heat the system at up to 300xc2x0 C.
EP-A-257 567 describes a polymer composition obtainable by emulsion polymerization of ethylenically unsaturated monomers, such as olefins, vinylaromatic compounds, xcex1,xcex2-ethylenically unsaturated carboxylic acids and their esters, ethylenically unsaturated dicarboxylic anhydrides and vinyl halides. During polymerization a water- or alkali-soluble or -dispersible resin having a number-average molecular weight of from about 500 to about 20,000 is added in order to influence the flow properties of the polymer composition. The resin is composed of olefins, vinylaromatic compounds, xcex1,xcex2-ethylenically unsaturated carboxylic acids and the esters thereof or ethylenically unsaturated dicarboxylic anhydrides. Ammonium hydroxide is indicated as the alkaline medium in which said resin is to be soluble or dispersible. The composition can be used to produce formaldehyde-free coatings on wooden substrates.
EP-A-576 128 describes repulpable adhesive compositions comprising an acid-rich polymer component and a low-acid polymer component. The acid-rich polymer component is based on a monomer mixture of from 40 to 95% of an alkyl acrylate or methacrylate and from 5 to 60% of an ethylenically unsaturated acid, such as acrylic or methacrylic acid. The low-acid polymer component is based on a monomer mixture of from 90 to 100% of an alkyl acrylate or methacrylate and from 0 to 10% of an ethylenically unsaturated acid. The compositions are prepared by aqueous emulsion polymerization, with the acid-rich polymer component being polymerized in the presence of the low-acid polymer component or vice versa. The pH of the composition is set at the desired level by adding ammonium hydroxide or sodium hydroxide. The composition can be used as a pressure-sensitive adhesive, laminating adhesive, adhesive for textile wovens, tiles and packaging, and as wood glue.
U.S. Pat. No. 5,314,943 describes a quick-curing formaldehyde-free binder composition of low viscosity for textile materials. The composition comprises a latex, which is a copolymer based on a vinylaromatic compound and a conjugated diene, and a water-soluble copolymer, which is obtained by copolymerizing a mixture of at least one ethylenically unsaturated polycarboxylic acid and at least one olefinically unsaturated monocarboxylic acid. The pH of the composition is set at from 5 to 9 by means of ammonium hydroxide or sodium hydroxide. The composition is employed as a binder for textile substrates.
U.S. Pat. No. 4,868,016 describes a composition based on at least one thermoplastic latex polymer which is insoluble in an aqueous alkaline medium and on at least one alkali-soluble polymer which is incompatible with the latex polymer. The latex polymer is a water-dispersed polymer which can be composed of acrylic or methacrylic esters, vinylaromatic compounds and vinyl esters and of from 0.5 to 3% by weight of an ethylenically unsaturated carboxylic acid as additional copolymer. The alkali-soluble polymer is also composed of these monomers, but contains from 10 to 60% by weight of an ethylenically unsaturated carboxylic acid. To establish the pH at  greater than 7 the composition can include ammonia, triethylamine, ethylamine or dimethylhydroxyethylamine. It can be used to provide substrates with a coating.
It is known that stable aqueous (meth)acrylate dispersions formed by emulsion polymerization in the presence of protective colloids can only be obtained if at least 50% of vinyl acetate, based on overall monomers, is incorporated by copolymerization. If the amount of vinyl acetate is less than 50%, agglomeration occurs. U.S. Pat. No. 4,670,505 describes as a solution to this problem a polyacrylate dispersion which is prepared by emulsion polymerization in the presence of from 0.1 to 5% by weight of at least one water soluble amino alcohol having 2 to 36 carbon atoms and from 0.04 to 5% by weight of a protective colloid, based in each case on overall monomers. The resulting latices are of low viscosity and improved pigment binding capacity, and are essentially free from gel specks and stable to shearing.
It is-an object of the present invention to provide shaped articles with formaldehyde-free binders which permit rapid curing at low temperature and which impart water resistance to the substrate.
We have found that this object is achieved by heat-curable compositions comprising at least one polymer (A1), which contains from 0 to 5% by weight of an 0,xcex2-ethylenically unsaturated mono- or dicarboxylic acid in copolymerized form and which is obtainable by free-radical polymerization in the presence of
a) at least one polymer (A2) obtainable by free-radical polymerization and containing from 15 to 100% by weight of an xcex1,xcex2-ethylenically unsaturated mono- or dicarboxylic acid in copolymerized form, and
b) at least one amine comprising at least one long chain having at least six carbons,
the weight ratio (based on solids) of polymer (A1) to polymer (A2) being from 7:1 to 1:7 and that of polymer (A2) to long-chain amine being from 20:1 to 2:1.
For the purposes of the present invention, alkyl is preferably straight-chain or branched C1-C18-alkyl, especially C1-C12-alkyl and, with particular preference, C1-C6-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-dodecyl or n-stearyl.
Hydroxyalkyl is preferably hydroxy-C1-C6-alkyl and, in particular, 2-hydroxyethyl and 2- or 3-hydroxypropyl.
Cycloalkyl is preferably C5-C7-cycloalkyl, especially cyclopentyl and cyclohexyl.
Aryl is preferably phenyl or naphthyl.
Polymer (A1):
The polymer A1 can be prepared using all monomers which can be polymerized by free-radical polymerization. In general, the polymer A1 is composed of:
from 60 to 100 parts by weight, based on the overall weight of the monomers for the polymer Al, of at least one copolymerizable monomer (principal monomer),
from 0 to 35 parts by weight, preferably from 0 to 20 parts by weight, of at least one functional monomer (comonomer) and from 0 to 5 parts by weight, preferably from 0 to 3 parts by weight, of an xcex1,xcex2-unsaturated mono- or dicarboxylic acid, preferably from 0 to 3% by weight.
The principal monomer is preferably selected from
esters of preferably C3-C6 xcex1,xcex2-monoethylenically unsaturated mono- or dicarboxylic acids, such as acrylic, methacrylic, maleic, fumaric and itaconic acid, with in general C1-C12-, preferably C1-C8- and especially C1-C4-alkanols.
Particular such esters are methyl, ethyl, n-butyl, isobutyl, tert-butyl and 2-ethylhexyl acrylate and methacrylate;
vinylaromatic compounds, such as styrene, xcex1-methylstyrene, o-chlorostyrene or vinyltoluenes;
vinyl esters of C1-C8 mono- or dicarboxylic acids, such as vinyl acetate, propionate, n-butyrate, laurate and stearate;
butadiene.
Particularly preferred principal monomers are methyl methacrylate, methyl acrylate, n-butyl methacrylate, t-butyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene and vinyl acetate.
Suitable comonomers are in particular:
linear 1-olefins, branched-chain 1-olefins or cyclic olefins, such as ethene, propene, butene, isobutene, pentene, cyclopentene, hexene, cyclohexene, octene, 2,4,4-trimethyl-1-pentene alone or mixed with 2,4,4-trimethyl-2-pentene, C8-C10 olefin, 1-dodecene, C12-C14 olefin, octadecene, 1-eicosene (C20), C20-C24 olefin; oligoolefins prepared by metallocene catalysis and having a terminal double bond, such as oligopropene, oligohexene and oligooctadecene; olefins prepared by cationic polymerization and with a high xcex1-olefin content, such as polyisobutene. Preferably, however, no ethene or linear 1-olefin is copolymerized into the polymer.
acrylonitrile, methacrylonitrile.
vinyl and allyl C1-C40-alkyl ethers where the alkyl can also carry substituents such as a hydroxyl, an amino or dialkylamino or one or more alkoxylate groups, examples being methyl, ethyl, propyl, isobutyl, 2-ethylhexyl, cyclohexyl, 4-hydroxybutyl, decyl, dodecyl, octadecyl, 2-(diethylamino)ethyl, 2-(di-n-butylamino)ethyl and methyldiglycol vinyl ether and the corresponding allyl ethers and/or mixtures thereof.
acrylamides and alkyl-substituted acrylamides, such as acrylamide, methacrylamide, N-tert-butylacrylamide, N-methyl(meth)acrylamide.
sulfo-containing monomers, such as allylsulfonic acid, methallylsulfonic acid, styrenesulfonate, vinylsulfonic acid, allyloxybenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, their corresponding alkali metal salts or ammonium salts, and mixtures thereof, and also sulfopropyl acrylate and sulfopropyl methacrylate.
C1-C4-hydroxyalkyl esters of C3-C6 mono- or dicarboxylic acids (see above), especially those of acrylic, methacrylic or maleic acid or their derivatives alkoxylated with from 2 to 50 mol of ethylene oxide, propylene oxide, butylene oxide or mixtures thereof, or esters of C1-C18 alcohols, alkoxylated with from 2 to 50 mol of ethylene oxide, propylene oxide, butylene oxide or mixtures thereof, with the abovementioned acids, examples being hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 1,4-butanediol monoacrylate, ethyldiglycol acrylate, methylpolyglycol acrylate (11 EO), (meth)acrylic esters of C13/C15 oxo alcohol reacted with 3,5,7,10 or 30 mol of ethylene oxide, and mixtures thereof.
vinylphosphonic acid, dimethyl vinylphosphonate and other phosphorus-containing monomers.
alkylaminoalkyl (meth)acrylates or alkylaminoalkyl (meth)acrylamides or quaternization products thereof, examples being 2-(N,N-dimethylamino)ethyl (meth)acrylate, 3-(N, N-dimethylamino)propyl (meth)acrylate, 2-(N,N,N-trimethylammonium)ethyl (meth)acrylate chloride, 2-dimethylaminoethyl(meth)acrylamide, 3-dimethylaminopropyl(meth)acrylamide, 3-trimethylammoniumpropyl(meth)acrylamide chloride.
allyl esters of C1-C30-monocarboxylic acids.
N-vinyl compounds, such as N-vinylformamide, N-vinyl-N-methylformamide, N-vinylpyrrolidone, N-vinylimidazole, 1-vinyl-2-methylimidazole, 1-vinyl-2-methylimidazoline, N-vinylcaprolactam, vinylcarbazole, 2-vinylpyridine, 4-vinylpyridine.
diallyldimethylammonium chloride, vinylidene chloride, vinyl chloride, acrolein, methacrolein.
1,3-diketo-containing monomers, such as acetoacetoxyethyl (meth)acrylate or diacetoneacrylamide, monomers containing urea groups, such as ureidoethyl (meth)acrylate, acrylamidoglycolic acid, methacrylamidoglycolate methyl ether.
silyl-containing monomers, such as trimethoxysilylpropyl methacrylate.
glycidyl-containing monomers, such as glycidyl methacrylate.
Particularly preferred comonomers are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate and hydroxyethyl methacrylate. Very particular preference is given to hydroxyethyl acrylate and hydroxyethyl methacrylate, especially in amounts of from 2 to 20% by weight, based on overall monomers A1.
The xcex1,xcex2-ethylenically unsaturated mono- and dicarboxylic acids are in particular those having 3 to 6 carbons. Examples are acrylic, methacrylic, crotonic, fumaric, maleic, 2-methylmaleic or itaconic acid and also monoesters of ethylenically unsaturated dicarboxylic acids, such as maleic acid monoalkyl esters of C1-C8-alkanols.
The polymers can be prepared by customary polymerization techniques. For all polymerization methods the customary apparatus is used, examples being stirred vessels, cascades of stirred vessels, autoclaves, tube reactors and compounders.
Polymerization is preferably carried out in the presence of compounds which form free radicals (initiators). The amount required of these compounds is preferably from 0.05 to 10, more preferably from 0.2 to 5% by weight, based on the monomers employed in the polymerization.
Examples of suitable polymerization initiators are peroxides, hydroperoxides, peroxodisulfates, percarbonates, peroxo esters, hydrogen peroxides and azo compounds. Examples of initiators, which may be soluble or insoluble in water, are hydrogen peroxide, dibenzoyl peroxide, dicyclohexyl peroxodicarbonate, dilauroyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl peroxide, acetylacetone peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl perneodecanoate, tert-amyl perpivalate, tert-butyl perpivalate, tert-butyl perneohexanoate, tert-butyl per-2-ethylhexanoate, tert-butyl perbenzoate, lithium, sodium, potassium and ammonium peroxodisulfates, azodiisobutyronitrile, 2,2xe2x80x2-azobis(2-amidinopropane) dihydrochloride, 2-(carbamoylazo)isobutyronitrile and 4,4-azobis(4-cyanovaleric acid). Other polymerization initiators which can be used are the known redox initiator systems, such as H2O2/ascorbic acid or t-butyl hydroperoxide/sodium hydroxymethanesulfinate.
The initiators can be employed alone or in a mixture with one another, such as mixtures of hydrogen peroxide and sodium peroxodisulfate. For polymerization in an aqueous medium it is preferred to employ water-soluble initiators.
To prepare polymers of low average molecular weight it is often judicious to carry out the copolymerization in the presence of regulators. Customary regulators can be used for this purpose, such as, for example, organic SH-containing compounds such as 2-mercaptoethanol, 2-mercaptopropanol, mercaptoacetic acid, tert-butylmercaptan, n-octylmercaptan, n-dodecylmercaptan and tert-dodecylmercaptan, hydroxylammonium salts, such as hydroxylammonium sulfate, formic acid, sodium bisulfite or isopropanol. The polymerization regulators are generally employed in amounts of from 0.05 to 5% by weight, based on the monomers.
To prepare copolymers of higher molecular mass it is often judicious to operate in the presence of crosslinkers in the course of the polymerization. Such crosslinkers are compounds having two or more ethylenically unsaturated groups, such as diacrylates or dimethacrylates of at least dihydric saturated alcohols, examples being ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,2-propylene glycol diacrylate, 1,2-propylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 3-methylpentanediol diacrylate and 3-methylpentanediol dimethacrylate. The acrylic and methacrylic esters of alcohols having more than 2 OH groups can also be employed as crosslinkers, examples being trimethylolpropane triacrylate and trimethylolpropane trimethacrylate. Another class of crosslinkers is that comprising diacrylates or dimethacrylates of polyethylene glycols or polypropylene glycols having molecular weights of in each case from 200 to 9000.
Apart from the homopolymers of ethylene oxide and/or propylene oxide it is also possible to employ block copolymers of ethylene oxide and propylene oxide or copolymers of ethylene oxide and propylene oxide which comprise the ethylene oxide and propylene oxide units in random distribution. The oligomers of ethylene oxide and/or propylene oxide are also suitable for the preparation of the crosslinkers, examples being diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate and/or tetraethylene glycol dimethacrylate.
Further suitable crosslinkers are vinyl acrylate, vinyl methacrylate, vinyl itaconate, divinyl adipate, butanediol divinyl ether, trimethylolpropane trivinyl ether, allyl acrylate, allyl methacrylate, pentaerythritol triallyl ether, triallylsucrose, pentaallylsucrose, methylenebis(meth)acrylamide, divinylethylene urea, divinylpropylene urea, divinylbenzene, divinyldioxane, triallyl cyanurate, tetraallylsilane, tetravinylsilane and bis- or polyacrylic siloxanes (for example, Tegomer(copyright) products from Th. Goldschmidt AG). The crosslinkers are preferably employed in amounts from 10 ppm to 5% by weight, based on the monomers to be polymerized.
The polymer A1 is usually prepared in water as the dispersing medium. However, water-miscible organic solvents, such as alcohols and ketones, examples being methanol, ethanol, n-propanol, isopropanol, n-butanol, acetone or methyl ethyl ketone, may also be present in a proportion of around 30% by volume. The result is a fine, stable polymer dispersion. The particle sizes can be determined by the methods customary for aqueous emulsion polymers. For example, the particle sizes determined by means of quasielastic light scattering are generally in the range from 30 to 1500 nm, preferably from 40 to 500 nm. The particle size distribution can be monomodal or polymodal.
The preparation of the polymer A1 is preferably carried out only with the acid-rich polymer A2 and the long-chain amine as the sole agents stabilizing the resulting dispersion particles. The polymer A2 and the long-chain amine form a polymeric ammonium salt which stabilizes the resulting polymer particles or polymer droplets and so leads to stable polymer dispersions with a low coagulum content.
Without the acid-rich polymer A2 the resulting polymer dispersions lack water resistance and have a poor thermal stability. Omission of the long-chain amine leads in many cases to coagulation of the polymerization mixture.
In addition to stabilization by the polymer A2 and the long-chain amine, however, it is also possible in the preparation of A1 to add surface-active auxiliaries such as emulsifiers or protective colloids.
Of the emulsifiers or protective colloids typically used for this purpose, anionic, nonionic, cationic and amphoteric emulsifiers are suitable. Preference is given to anionic emulsifiers, such as alkylbenzenesulfonic acids, sulfonated fatty acids, sulfosuccinates, fatty alcohol sulfates, alkylphenol sulfates and fatty alcohol ether sulfates. Examples of nonionic emulsifiers which can be used are alkylphenol ethoxylates, primary alcohol ethoxylates, fatty acid ethoxylates, alkanolamide ethoxylates, EO/PO block copolymers and alkyl polyglucosides. Examples of cationic and/or amphoteric emulsifiers used are quaternized amino-alkoxylates, alkylbetaines, alkylamidobetaines and sulfobetaines.
Examples of typical protective colloids are cellulose derivatives, polyethylene glycol, polypropylene glycol, copolymers of ethylene glycol and propylene glycol, polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, starch and starch derivatives, dextran, polyvinylpyrrolidone, polyvinylpyridine, polyethyleneimine, polyvinylimidazole, polyvinylsuccinimide, polyvinyl-2-methylsuccinimide, polyvinyl-1,3-oxazolid-2-one and polyvinyl-2-methylimidazoline.
The emulsifiers or protective colloids are usually used in concentrations of less than 5% by weight, based on the monomers. It is preferred to work without emulsifiers or protective colloids.
The monomers can be neutralized in whole or in part, prior to or during polymerization, by means of customary inorganic or organic bases. Examples of suitable bases are alkali or alkaline earth metal compounds, such as sodium, potassium or calcium hydroxide, sodium carbonate, ammonia and primary, secondary or tertiary amines, such as di- or triethanolamine.
It is particularly preferred not to carry out neutralization before and during the polymerization. Even after the polymerization it is preferred not to add any neutralizing agent, apart from the alkanolamine which may be added.
The polymerization can be carried out continuously or discontinuously in a customary manner and in accordance with a large number of variants.
When the above-described polymerization process is employed in the presence of a polymer (A2) and the long-chain amine, polymers (A1) having a weight-average molecular weight of from 1000 to 5,000,000, preferably from 5000 to 2,000,000 are obtained. A readily available measure of the average molecular weight of a polymer is its K value. The K value is a relative viscosity number which is determined in analogy to DIN 53726. It comprises the flow rate of the pure solvent relative to the flow rate of a solution of polymer A2 in this solvent. A high K value corresponds to a high average molecular weight (cf. Cellulosechemie, Vol. 13, (1932), pp. 58-64 and Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 23, pp. 967-968). The K values are generally in the range from 15 to 150 (1% strength by weight in dimethylformamide). The emulsion polymerization can be carried out so that the solids content is in the range from 20 to 70%, preferably from 30 to 60%, by volume.
From 15 to 100% by weight of the polymer (A2), preferably from 20 to 100% by weight, in particular from 40 to 100% by weight and, with particular preference from 60 to 100% by weight is composed of at least one xcex1,xcex2-ethylenically unsaturated mono- or dicarboxylic acid. The polymer may also be present in part or completely in the form of a salt; the acidic form is preferred. The solubility in water of the polymer in the acidic form is preferably  greater than 10 g/l (at 25xc2x0 C.).
The weight-average molecular weight of the polymer (A2) is more than 500 and generally less than 5 million. The K values of the polymers (in accordance with H. Fikentscher, Cellulose-Chemie 13 (1932), pp. 58-64, 71 and 74), which are a measure of the molecular weight, are in general in the range from 10 to 150 (measured in 1% strength by weight aqueous solution). The polymer has on average generally at least 4 carboxylic acid groups, or salt groups derived therefrom, per polymer chain.
Ethylenically unsaturated carboxylic acids which can be used have already been specified above in connection with polymer (A1). Particular preference is given to polymers which include maleic acid, such as copolymers of maleic and acrylic acids. The polymers can also be obtained starting from ethylenically unsaturated mono- or dicarboxylic anhydrides alone or in a mixture with the abovementioned carboxylic acids. Under the polymerization conditions, for example in solution or emulsion polymerization in an aqueous medium, or subsequent to the polymerization, the anhydride functions are converted to carboxylic acid groups by reaction with an acid or base. Ethylenically unsaturated carboxylic anhydrides that can be used are, in particular, maleic, itaconic, acrylic and methacrylic anhydrides.
In addition to the mono- or dicarboxylic acids the polymer (A2) can also include, in copolymerized form, from 0 to 85% by weight, preferably from 0 to 80% by weight, in particular from 0 to 60% by weight and with particular preference from 0 to 40% by weight of at least one further monomer. Monomers which can be used have already been specified above in connection with polymer (A1). Preference is given to methyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, acrylamide, acrylonitrile and vinyl acetate.
The polymerization procedure and auxiliaries have already been described above in connection with polymer (A1).
In addition to the polymerization techniques specified above in connection with polymer (A1), the polymers (A2) can also be obtained by a solution polymerization.
The use of aqueous free-radical solution polymerization gives water-soluble polymers and copolymers A2, preferably starting from 50 to 100% by weight of the abovementioned carboxylic acids, carboxylic anhydrides, monoesters or a mixture of two or more of these compounds. Their weight-average molecular weight is generally in the range from 500 to 1,000,000, preferably from 2000 to 200,000. The K values of the polymers are generally in the range from 10 to 150, preferably from 12 to 100 (measured in 1% strength by weight solution in water). The solids content is generally in the range from 10 to 80% by weight, preferably from 20 to 65% by weight. The polymerization can be conducted at from 20 to 300xc2x0 C., preferably from 60 to 200xc2x0 C. The solution polymerization is carried out in a customary manner, as described, for example, in EP-A-75 820 or DE-A-36 20 149.
The polymer (A2) can also be obtained by grafting maleic acid or maleic anhydride, or a monomer mixture comprising maleic acid or maleic anhydride, onto a graft base. Examples of suitable graft bases are monosaccharides, oligosaccharides, modified polysaccharides and alkyl polyglycol ethers. Examples of such graft polymers are described in DE-A-4 003 172 and EP-A-116 930.
The polymer A2 can also be prepared in a two-stage procedure directly prior to the preparation of the polymer A1 in the same reaction vessel.
The long-chain amine is preferably an amine of the formula
RxNRyRz
where Rx is C6-C22-alkyl, C6-C22-alkenyl, aryl-C6-C22-alkyl or aryl-C6-C22-alkenyl and the alkenyl can have 1 to 3 double bonds, Ry and Rz, which may be identical or different, are H, "Parenopenst"CH2CH2O"Parenclosest"nH, where n is 1 to 25, or C5-C7-cycloalkyl which is unsubstituted or substituted by at least one hydroxyl, or are as defined for Rx or together are a 5- to 7-membered ring which may contain at least one further heteroatom selected from O, N and S.
Preferred radicals Rx are those having 8 to 22 carbons. The long-chain amine is in particular selected from compounds of the above formula in which Rx is C6-C22-alkyl or C6-C22-alkenyl (having preferably 1 or 2 double bonds) and Ry and Rz, which are identical or different, are H or "Parenopenst"CH2CH2O"Parenclosest"n H. n is preferably 1 to 20, especially 1 to 10.
Examples of suitable long-chain amines are those ethoxylated amines marketed by AKZO under the name xe2x80x9cEthomeenxe2x80x9d such as Ethomeen C/15, a polyoxyethylene-(5)-cocoamine, or Ethomeen S/12, an oleylbis (2-hydroxyethyl)amine, or Ethomeen T/25, a polyoxyethylene-(15)-tallowamine.
Products of this kind are also available from other manufacturers. Further examples which may be mentioned at this point are Lutensol FA 12 from BASF, a polyoxyethylene-(12)-oleylamine, or Noramox 0.7 from Pierrefitte-Auby, a polyoxyethylene-(7)-oleylamine.
Ethoxylated long-chain mono- and diamines are preferred. For the preparation of the novel compositions, however, it is also possible to use long-chain primary, secondary or tertiary aliphatic amines. Examples of these are the AKZO products Armeen DMOD (oleyldimethylamine), Armeen M2C (dicocomethylamine), Armeen NCMD (N-cocomorpholine), Armeen 2C (dicocoamine) or Armeen 12D (n-dodecylamine).
The composition can if desired also include at least one alkanolamine having at least two hydroxyls. The addition of the alkanolamine brings about more rapid curing of the novel compositions at a given curing temperature, or curing at a lower temperature with a predetermined curing time. In addition, adding an alkanolamine improves the film-forming capacity of a composition.
Suitable alkanolamines are those of the formula: 
where Ra is H, C1-C5-alkyl or C1-C10-hydroxyalkyl and Rb and Rc are C1-C10-hydroxyalkyl.
With particular preference, Rb and Rc independently are a C2-C5-hydroxyalkyl and Ra is H, C1-C5-alkyl or C2-C5-hydroxyalkyl.
Examples of alkanolamines are diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, methyldiethanol amine, butyldiethanolamine and methyldiisopropanolamine. Triethanolamine is particularly preferred.
Also suitable are alkanolamines selected from water-soluble, linear or branched aliphatic compounds which comprise per molecule at least two functional amino groups of type (a) or (b) 
where R is hydroxyalkyl and Rxe2x80x2 is alkyl. Such compounds preferably comprise at least one compound of the formula I: 
where
A is C2-C18-alkylene which is unsubstituted or substituted by one or more groups selected independently from alkyl, hydroxyalkyl, cycloalkyl, OH and NR6R7, where R6 and R7 independently are H, hydroxyalkyl or alkyl, and uninterrupted or interrupted by one or more oxygens and/or NR5 groups, where R5 is H, hydroxyalkyl, (CH2)nNR6R7, where n is 2 to 5 and R6 and R7 are as defined above, or alkyl, which in turn is interrupted by one or more NR5 groups where R5 is as defined above and/or is substituted by one or more NR6R7 groups where R6 and R7 are as defined above; or A is a radical of the formula: 
xe2x80x83where
o, q and s independently are 0 or an integer from 1 to 6,
p and r independently are 1 or 2 and
t is 0, 1 or 2,
where the cycloaliphatic radicals can also be substituted by 1, 2 or 3 alkyls, and
R1, R2 and R3 and R4 independently are H, hydroxyalkyl, alkyl or cycloalkyl, the compounds having at least two or preferably at least three hydroxyalkyls per molecule.
Particular preference is given to:
(1) compounds of the formula Ia 
xe2x80x83where
A1 is C2-C12-alkylene which is unsubstituted or substituted by at least one alkyl and/or at least one NR6R7 group where R6 and R7 independently are alkyl or hydroxyalkyl, and
R1, R2, R3 and R4 independently are hydroxyalkyl or H, or one of R1 and R2 and/or one of R3 and R4 is alkyl or cycloalkyl.
Particularly useful compounds of this type are those of the following formulae: 
where x is 2 to 12, especially 2, 3, 6, 8, 10 or 12, 
Compounds of the formula Ia also include the aminals of the formula 
(2) Compounds of the formula Ib 
xe2x80x83where
A2 is C2-C8-alkylene which is interrupted by at least one group NR5 where R5 (or each R5 independently) is hydroxyalkyl or alkyl, and
R1, R2, R3 and R4 independently are hydroxyalkyl or H.
The radical A2 is preferably interrupted by one or two groups NR5. Particularly useful compounds of this type are those of the following formulae: 
(3) Compounds of the formula Ic: 
xe2x80x83where
A3 is C2-C8-alkylene which is interrupted by at least one group NR5 where R5 is H, hydroxyalkyl or CH2CH2NR6R7,
R1, R2, R3 and R4 independently are alkyl which is uninterrupted or interrupted by at least one group NR5 and/or unsubstituted or substituted by at least one group NR6R7,
R5 is H, hydroxyalkyl or xe2x80x94R8NR6R7, and
R6 and R7 independently are H, hydroxyalkyl or xe2x80x94R8NR6R7,
R8 is an ethylene or propylene radical, and where (on average) at least 30%, in particular  greater than 60% and
preferably  greater than 80% of the (hydroxyalkylatable) nitrogens carry a hydroxyalkyl.
The C2-C8-alkylene group is preferably interrupted by at least two groups NR5. Particularly useful compounds of this type are reaction products of ethylene oxide with polyethyleneimines of different molecular weights, containing two or more structural units NR6R7 and NR5. Polyethyleneimines which can be used are those whose weight-average molecular weight is in the range from 400 to 2,000,000. The diagrammatic formula below is intended to illustrate compounds of this type: 
where
R5 is H, hydroxyethyl or xe2x80x94R8NR6R7 and R6 and R7 are H, hydroxyethyl or xe2x80x94R8NR6R7 and R8 is (CH2)2, in which on average  greater than 40%, especially  greater than 60% and with particular preference  greater than 80% of the ethoxylable NH functions of the polyethyleneimine have been reacted with ethylene oxide.
(4) Compounds of the formula Ie 
xe2x80x83where
A5 is C6-C18-alkylene which is interrupted by at least one group NR5 where R5 is (CH2)nNR6R7 or alkyl which is uninterrupted or interrupted by at least one group NR5 where R5 is (CH2)nR6R7 or alkyl and/or is unsubstituted or substituted by at least one group NR6R7,
n is 2 or 3 and
R1, R2, R3, R4, R6 and R7 independently are hydroxyalkyl or H.
Particularly useful compounds of this type are polyamines of the formulae: 
(5) Compounds of the formula If 
xe2x80x83where
A6 is C2-C12-alkylene which is interrupted by at least one oxygen and
R1, R2, R3 and R4 independently are hydroxyalkyl or H.
The alkylene chain is preferably interrupted by 1, 2 or 3 oxygens. Particularly useful compounds of this type are the compounds of the following formulae: 
(6) Compounds of the formula Ig, 
xe2x80x83where
o, q and s independently are 0 or an integer from 1 to 6;
p and r independently are 1 or 2 and
t is 0, 1 or 2,
it being possible for the cycloaliphatic rings to be substituted by 1, 2 or 3 alkyls, and
R1, R2, R3 and R4 independently are hydroxyalkyl or H.
Particularly useful compounds of this type are 
(7) Polyalkanolamines which are obtainable by condensing di- or trialkanolamines with themselves or with one another, alone or in the presence of alcohols or amines having a functionality of one or more.
An example of such oligomeric or polymeric compounds is the condensation product prepared from triethanol which is represented in idealized form by the following diagrammatic formula: 
The compounds of the formula Ia, Ib (with the exception of the abovementioned aminals), Ic, Id, Ie, If and Ig can be prepared by reacting the corresponding polyamines with alkylene oxides.
The reaction of amines with alkylene oxides, especially ethylene oxide and propylene oxide, to the corresponding alkanolamines is known in principle. For this purpose the amines are reacted in the presence of a proton donor, generally water, with the alkylene oxides, generally at from 30 to 120xc2x0 C., under atmospheric or superatmospheric pressure, preferably at from 1 to 5 bar, using about one equivalent of the alkylene oxide per Nxe2x80x94H function to be alkoxylated. For near-complete alkoxylation it is possible to use a small excess of alkylene oxide, although it is preferred to employ the stoichiometric amount or even a slight deficit of the alkylene oxide relative to the Nxe2x80x94H functions. Alkoxylation can be carried out with one alkylene oxide or with a mixture of two or more alkylene oxides. Alternatively, alkoxylation can be carried out with two or more alkylene oxides in succession.
Suitable catalysts other than water are alcohols or acids, although water is preferred (regarding the alkoxylation of amines cf. N.Schxc3x6nfeld, Grenzflxc3xa4chenaktive Ethylenoxid-Addukte [Surface-active ethylene oxide adducts], pp. 29-33, Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart 1976 or S. P. McManus et al., Synth. Comm. 3, (1973) 177).
The amount of water employed as catalyst and/or solvent may vary depending on requirements. In the case of liquid amines of low viscosity amounts of water from 1 to 5% are sufficient to catalyze the reaction. Solid, highly viscous or polymeric amines are advantageously reacted as solutions or dispersions in water; in this case the amount of water can be from 10 to 90%.
Under the conditions described for the alkoxylation in the presence of water, essentially only the xe2x80x94NH groups are reacted. Alkoxylation of the resulting OH groups does not, in general, take place, so that essentially a monoalkoxylation of the NH groups takes place (in other words, not more than 1 mol of alkylene oxide is added on per mol of NH).
The mean degree of alkoxylation of the active NH groups is preferably  greater than 75% in the case of compounds having less than nitrogens per molecule.
Examples of starting polyamines which can be used are xcex1,xcfx89-oligomethylenediamines, such as 1,2-ethylenediamine, 1,3-propanediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecamethylenediamine, 2,2-dimethyl-1,3-propanediamine, 1,2-propanediamine, 2-(ethylamino)ethylamine, 2-(methylamino)propylamine, N-(2-aminoethyl)-1,2-ethanediamine, N-(2-aminoethyl)-1,3-propanediamine, N-(2-aminoethyl)-N-methylpropanediamine, N,N-bis-(3-aminopropyl)ethylenediamine, 4-aminoethyl-1,8-octanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 2,2,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, 1,3-diaminopentane, 3-isopropylaminopropylamine, triethylenetetramine or tetraethylenepentamine.
Oligo- and poly-N-(xcex2-hydroxyethyl)amino compounds (aminals) can also be prepared by condensing aliphatic dialdehydes and diethanolamine.
Poly-N-(xcex2-hydroxyethyl)amino compounds (8) are obtained as described, for example, in U.S. Pat. No. 4,505,839 and in DE-A-3 206 459 by thermal condensation of triethanolamine to give poly(triethanolamine) or by thermal condensation of alkanolamines to give hydroxyl-containing polyethers. The condensation of the alkanolamines can also be carried out, as described in DE-A-1 243 874, in the presence of primary or secondary amines or alcohols having a functionality of one or more. Depending on the condensation conditions the molecular weight of these products and thus the viscosity can be varied within a broad range.
The weight-average molecular weights of these polycondensates are usually from 200 to 100,000.
The compounds of the formulae Ie can be prepared by alkoxylation from what are known as dendrimer polyamines, whose synthesis by Michael addition of aliphatic diamines onto acrylonitrile and subsequent catalytic hydrogenation is described in WO 93/14147. One example of such compounds is the hydrogenated adduct of 4 mol of acrylonitrile and ethylenediamine. This hexamine having 4 primary aminos can be reacted further in a similar manner to give the N-14 amine having 8 primary aminos. Instead of ethylenediamine, other aliphatic di- and polyamines can also be employed.
Amino-containing polymers such as polyethyleneimine can also be reacted with ethylene oxide in aqueous solution to form useful poly-N-(xcex2-hydroxyethyl)amino compounds, the degree of conversion of the NH functions present being generally  greater than 40%, especially  greater than 60% and preferably  greater than 80%. The preparation of polyethyleneimine is general knowledge. Polyethyleneimines in the molecular weight range Mw=800 to 2,000,000, for example, are obtainable from BASF under the name Lupasol(copyright). Polyethyleneimines generally consist of branched polymer chains and therefore contain primary, secondary and tertiary aminos. Their ratio is usually about 1:2:1. At very low molecular weights, however, higher proportions of primary aminos are also possible. Also suitable for this application are substantially linear polyethyleneimines which are obtainable by special preparation techniques.
Polymeric alkyleneimines having primary and/or secondary aminos, which following alkoxylation can be used in the novel compositions, are described in xe2x80x9cEncyclopedia of Polymer Science and Engineeringxe2x80x9d, H. Mark (Editor), Revised Edition, Volume 1, pp. 680-739, John Wiley and Sons Inc., New York, 1985.
It is also possible to prepare hydroxyalkyl-substituted polyalkyleneimines by polymerizing N-hydroxyalkylaziridines.
Alkoxylated allylamine polymers and copolymers can also be used in the novel compositions.
The compounds of the formula If can be prepared starting from oxamines, such as 4,7-dioxadecane-1,10-diamine, 4,9-dioxadecane-1,12-diamine, 4,11-dioxatetradecane-1,14-diamine, 4, 9-dioxadodecane-1,12-diamine and 4,7,10-trioxatridecane-1,13-diamine. Other suitable starting amines are polyoxyalkylenamines, which are marketed by Huntsman under the name Jeffamine(copyright). Examples of these are the diamines Jeffamine D-230, Jeffamine-D-400, Jeffamine D-2000, Jeffamine D-4000, Jeffamine ED-600, Jeffamine ED-900, Jeffamine ED-2001 and Jeffamine EDR-148 and the triamines Jeffamine T-403, Jeffamine T-3000 and Jeffamine T-5000.
Reaction products of aromatic polyamines with alkylene oxide are also suitable in principle for use in the novel compositions.
The polymers (A1) and (A2) are preferably employed in a weight ratio of from 5:1 to 1:5 and with particular preference from 3:1 to 1:3 (based on nonvolatile fractions).
The weight ratio of polymer (A2) to long-chain amine is from 20:1 to 2:1 (based on nonvolatile fractions), preferably from 10:1 to 3:1.
The weight ratio of polymer (A2) to alkanolamine (if present) is preferably from 100:1 to 1:1, especially from 50:1 to 2:1 and, with particular preference, from 30:1 to 2.5:1 (based in each case on nonvolatile fractions).
Particularly preferred proportions are as follows:
40-60 parts by weight of polymer (A1)
20-40 parts by weight of polymer (A2)
6-10 parts by weight of long-chain amine, and if used
0-15 parts by weight of alkanolamine.
The alkanolamine is preferably added to the novel composition after the preparation. It can be added in undiluted form or as an aqueous solution. An alternative possibility is to prepare the novel composition in the presence of an alkanolamine.
The pH of the novel compositions is from 0 to 9, preferably from 0.5 to 6, with particular preference from 1 to 4. A low pH favors the heat curing of the compositions.
At a content of active ingredients of 40% by weight, the viscosity of the novel aqueous compositions is generally in the range from 10 to 100,000 mPa.s, measured in a rotary viscometer in accordance with DIN 53019 at 23xc2x0 C. and at a shear rate of 250 sxe2x88x921. Preference is given to viscosities of from 20 to 20,000 mPa.s, especially from 30 to 5000 mPa.s.
The novel compositions have a nonvolatile content in the range from 20 to 75% by weight, preferably from 40 to 70% by weight.
The novel compositions may include a reaction accelerator but preferably do not. Examples of suitable reaction accelerators are alkali metal hypophosphites, phosphites, polyphosphates and dihydrogenphosphates, polyphosphoric acid, hypophosphoric acid, phosphoric acid, alkylphosphinic acid or oligomers or polymers of these salts and acids.
Further suitable catalysts are strong acids such as sulfuric and p-toluenesulfonic acids. Also suitable are polymeric sulfonic acids, such as poly(acrylamido-2-methylpropanesulfonic acid), poly(vinylsulfonic acid), poly(p-styrenesulfonic acid), poly(sulfopropyl methacrylate) and polymeric phosphonic acids such as poly(vinylphosphonic acid), for example, and also copolymers derived therefrom with the above-described comonomers.
It is additionally possible to incorporate the acceleration-inducing sulfonic acids or phosphonic acids into the acid-containing polymer (A2) by using the corresponding monomers, such as acryloamido-2-methylpropanesulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, sulfopropyl methacrylate or vinylphosphonic acid, as comonomer when preparing the polymeric carboxylic acids.
Further suitable catalysts are organotitanates and organozirconates, such as triethanol titanate, titanium chelate ETAM and tetrabutyl zirconate, which are marketed, for example, by Hxc3xcls.
In addition, the novel compositions may depending on their intended use comprise customary additives, such as bactericides or fungicides, for example. In addition, they may comprise hydrophobicizing agents for increasing the water resistance of the treated substrates. Suitable hydrophobicizing agents are customary aqueous paraffin dispersions or silicones. The compositions may also include wetting agents, thickeners, plasticizers, retention agents, pigments and fillers.
Finally, the novel compositions can comprise customary agents providing protection against fire, such as aluminum silicates, aluminum hydroxides, borates and/or phosphates.
In many cases the compositions also comprise coupling reagents, such as alkoxysilanes, an example being 3-aminopropyltriethoxysilane, soluble or emulsifiable oils as lubricants and dust binders, and also wetting auxiliaries.
The novel compositions can also be employed in a blend of other binders such as, for example, urea-, melamine- or phenyl-formaldehyde resins, and with epoxy resins.
The novel compositions are formaldehyde-free. Formaldehyde-free means that the novel compositions contain no substantial amounts of formaldehyde and also that on drying and/or curing no substantial amounts of formaldehyde are released. In general, the formaldehyde content of the compositions is  less than 100 ppm. The compositions make it possible to prepare shaped articles requiring a short curing time, and give the shaped articles excellent mechanical properties.
The novel heat-curable, formaldehyde-free compositions are essentially uncrosslinked in use and are therefore thermoplastic. If necessary, however, a small degree of precrosslinking can be established by using, for example, monomers having two or more polymerizable groups.
On heating, the water in the composition evaporates and the composition cures. These processes may take place in succession or simultaneously. By curing is meant in this context the chemical alteration of the composition: for example, crosslinking by formation of covalent bonds between the various constituents of the compositions, formation of ionic interactions and clusters, formation of hydrogen bonds. Curing may also involve physical changes in the binder, such as phase transformations or phase inversion.
Curing takes place at from 75 to 250xc2x0 C., preferably from 90 to 200xc2x0 C., and, with particular preference, from 100 to 180xc2x0 C. The duration and level of heating influence the degree of curing. An advantage of the novel compositions is that they can be cured at comparatively low temperatures.
Curing may also take place in two or more stages. For instance, in a first step the curing temperature and time can be chosen so that only a low degree of curing is obtained, and substantially complete curing takes place in a second step. This second step may be effected in spatial and temporal separation from the first step. This enables the novel compositions to be used, for example, to produce semifinished goods, impregnated with binder, which can be shaped and cured to completion at a different site.
The compositions are used in particular as binders for the production of shaped articles made from fibers, slivers or chips, which can be of renewable raw materials or of synthetic or natural fibers, for example from clothing wastes. As renewable raw materials mention may be made in particular of sisal, jute, flax, coconut fibers, kenaf, banana fibers, hemp and cork. Wood fibers or wood chips are particularly preferred.
The shaped articles preferably have a density of from 0.2 to 1.4 g/cm3 at 23xc2x0 C.
Suitable shaped articles are, in particular, sheets and irregularly contoured parts. Their thickness is generally at least 1 mm, preferably at least 2 mm, and their surface area is typically from 200 to 200,000 cm2. Particularly suitable such articles are interior automotive parts, such as interior door trim, dashboards, parcel shelves.
The amount by weight of the binder used is generally from 0.5 to 40% by weight, preferably from 1 to 30% by weight (in terms of binder solids), based on the substrate (fibers, slivers or chips).
The fibers, slivers or chips can be coated directly with the binder or mixed with the aqueous binder. The viscosity of the aqueous binder is preferably established (especially in the case of the production of shaped articles from wood fibers or wood chips) at from 10 to 10,000, more preferably from 50 to 5000 and, with very particular preference, from 100 to 2500 mPa.s (DIN 53019, rotary viscometer 250 sxe2x88x921).
The mixture of fibers, slivers and chips and the binder can be initially dried at from 10 to 150xc2x0 C., for example, and then pressed at from 50 to 250xc2x0 C., preferably from 100 to 240xc2x0 C. and, with particular preference, from 120 to 225xc2x0 C. and at pressures generally from 2 to 1000 bar, preferably from 10 to 750 bar and, with particular preference, from 20 to 500 bar to give the shaped articles.
The binders are particularly suitable for producing woodbase materials such as wood chipboards and wood fiberboards (cf. Ullmanns Encyclopxc3xa4die der technischen Chemie, 4th edition 1976, Volume 12, pp. 709-727), which can be produced by gluing disintegrated wood such as wood chips and wood fibers, for example. The water resistance of woodbase materials can be enhanced by adding to the binder a customary commercial aqueous paraffin dispersion or other hydrophobicizing agents, or adding said hydrophobicizing agents beforehand or subsequently to the fibers, slivers or chips.
Chipboard production is widely known and is described, for example, in H. J. Deppe, K. Ernst, Taschenbuch der Spanplattentechnik, 2nd edition, Verlag Leinfelden 1982.
It is preferred to use chips whose average size is from 0.1 to 4 mm, in particular from 0.2 to 2 mm, and which contain less than 6% by weight of water. However, it is also possible to employ considerably coarser chips and those with a higher moisture content. The binder is applied with great uniformity to the wood chips, the weight ratio binder solids/wood chips preferably being from 0.02:1 to 0.3:1. Uniform distribution can be achieved, for example, by spraying the binder in finely divided form onto the chips.
The glued wood chips are then spread out to form a layer with a highly uniform surface, the thickness of the layer being guided by the desired thickness of the finished chipboard. The scattered layer is pressed at from 100 to 250xc2x0 C., preferably from 120 to 225xc2x0 C., by applying pressures of usually from 10 to 750 bar, to form a board. The required press times may vary within a wide range and are in general from 15 seconds to 30 minutes.
The wood fibers of suitable quality required to produce medium-density fiberboard (MDF) panels from the binders can be prepared from bark-free wood chips by grinding in special mills or refiners at about 180xc2x0 C.
For gluing, the wood fibers are generally swirled up in a stream of air and the binder is sprayed into the stream of fibers thus generated (xe2x80x9cblow-linexe2x80x9d process). The proportion of wood fibers to binder, based on the dry-matter content or solids content, is usually from 40:1 to 2:1, preferably from 20:1 to 4:1. The glued fibers are dried in the stream of fibers at from 130 to 180xc2x0 C., for example, spread out to form a fiber web and pressed at pressures from 10 to 50 bar to form sheets or shaped articles.
The glued wood fibers can also be processed, as described in DE-A 2 417 243, for example, into a transportable fiber mat. This semifinished product can then be processed further in a second, temporally and spatially separate step to form sheets or shaped articles, such as motor vehicle interior door trim panels.
Other natural fiber substances as well, such as sisal, jute, hemp, flax, coconut fibers, banana fibers and other natural fibers, can be processed with the binders to form sheets and shaped parts. The natural fiber materials can also be used in mixtures with plastic fibers, such as polypropylene, polyethylene, polyesters, polyamides or polyacrylonitrile. In this case the plastic fibers may also function as cobinders in addition to the novel binder. The proportion of plastic fibers is preferably less than 50% by weight, in particular less than 30% by weight and, with very particular preference, less than 10% by weight, based on all chips, slivers or fibers. The fibers can be processed by the methods used for the wood fiberboards. Alternatively, preformed natural fiber mats can be impregnated with the novel binders, with or without the addition of a wetting auxiliary. The impregnated mats are then pressed, in the binder-moist or predried state, at from 100 to 250xc2x0 C. and at pressures from 10 to 100 bar, for example, to form sheets or shaped parts.
The substrates impregnated with the novel binders preferably have a residual moisture content, on pressing, of 3-20% by weight, based on the substrate to be bound.
The shaped articles obtained in accordance with the invention feature low water absorption, little increase in thickness (swelling) after storage in water, and good strength and are formaldehyde-free.
In addition, the novel compositions can be used as binders for coating and impregnating compositions for sheets of organic and/or inorganic fibers, nonfibrous mineral fillers, and also starch and/or aqueous polymer dispersions. The coating and the impregnating compositions give the sheets a high flexural modulus. The production of such sheets is known.
Sheets of this kind are usually employed as soundproofing panels. The thickness of the sheets is usually in the range from about 5 to 30 mm, preferably from 10 to 25 mm. The edge length of the square or rectangular sheets is usually in the range from 200 to 2000 mm.
In addition, the novel compositions may comprise the auxiliaries customary in coating and impregnation technology. Examples of such auxiliaries are finely divided inert fillers, such as aluminum silicates, quartz, precipitated or pyrogenic silica, light and heavy spar, talc, dolomite or calcium carbonate; color-imparting pigments, such as titanium white, zinc white, iron oxide black, etc., foam inhibitors, such as modified dimethylpolysiloxanes, and adhesion promoters and preservatives.
The components of the novel composition are present in the coating composition in general in an amount from 1 to 65% by weight. The proportion of the inert fillers is generally from 0 to 85% by weight, while that of water is at least 10% by weight.
The compositions are employed in a customary manner by application to a substrate, for example by spraying, rolling, pouring or impregnating. The amounts applied, based on the dry content of the composition, are in general from 2 to 100 g/m2.
The amounts of additives to be employed are known to the skilled worker and depend in each individual case on the desired properties and on the intended use.
The novel compositions are also useful as binders for insulating materials made from inorganic fibers, such as mineral fibers and glass fibers. Such insulating materials are produced industrially by spinning from melts of the corresponding mineral raw materials: see U.S. Pat. No. 2,550,465, U.S. Pat. No. 2,604,427, U.S. Pat. No. 2,830,648, EP-A-354 913 and EP-A-567 480. The composition is then sprayed onto the freshly produced and still hot inorganic fibers. Then the water evaporates substantially and the composition remains adhering, in an essentially uncured state, as a viscous mass on the fibers. A continuous, binder-containing fiber mat produced in this way is transported on through a curing oven by means of suitable conveyor belts. There, the mat cures at from about 100 to 200xc2x0 C. to form a rigid matrix. After curing, the insulating mats are finished appropriately.
The predominant proportion of the mineral or glass fibers used in the insulating materials has a diameter in the range from 0.5 to 20 xcexcm and a length in the range from 0.5 to 10 cm.
The novel compositions are suitable, moreover, as binders for fiber webs.
Examples of fiber webs are webs of cellulose, cellulose acetate, esters and ethers of cellulose, cotton, hemp, animal fibers, such as wool or hair, and especially nonwovens of synthetic or inorganic fibers, for example aramid, carbon, polyacrylonitrile, polyester, mineral, PVC or glass fibers.
When used as binders for fiber webs the novel compositions may, for example, include the following additives: silicates, silicones, boron-containing compounds, lubricants, wetting agents.
Glass fiber webs are preferred. The unbonded fiber webs (raw fiber webs), especially those of glass fibers, are bondedxe2x80x94that is, consolidatedxe2x80x94by the novel binder.
The novel binder is preferably applied to the raw fiber web, by coating, impregnating or soaking, for example, in a fiber/binder (solids) weight ratio of from 10:1 to 1:1, more preferably from 6:1 to 3:1.
In this case the binder is preferably used in the form of a dilute aqueous formulation containing from 95 to 40% by weight of water.
Application of the binder to the raw fiber web is generally followed by drying at, preferably, from 100 to 400xc2x0 C., especially from 130 to 280xc2x0 C., and, with very particular preference, at from 130 to 230xc2x0 C., over a period of preferably 10 seconds to 10 minutes, in particular from 10 seconds to 3 minutes.
The bonded fiber web obtained has high strength in the dry and wet states. In particular, the novel binders permit short drying times and also low drying temperatures.
The bonded fiber webs, especially glass fiber webs, are suitable for use as or in roofing membranes, as base materials for wallpapers or as inliners or base material for floor coverings made, for example, from PVC.
In the case of use as roofing membranes the bonded fiber webs are generally coated with bitumen.
The aqueous compositions of this invention can also be used to produce foamed boards or shaped articles. To this end, the water present in the composition is initially removed at temperatures of  less than 100xc2x0 C. down to a level of  less than 20% by weight. The resulting viscous composition is then foamed at temperatures of  greater than 100xc2x0 C., preferably at from 120 to 300xc2x0 C. The residual water still present in the mixture and/or the gaseous products formed in the course of the curing reaction, for example, may act as blowing agents. Alternatively, commercial blowing agents can be added. The resulting crosslinked polymer foams can be used, for example, for thermal and acoustic insulation.
The compositions of this invention can be used for impregnating paper, which is subsequently dried under gentle conditions, to produce laminates, for example for decorative applications, according to known processes. In a second step these laminates are applied to the substrate to be coated, by a lamination with heat and pressure, under conditions chosen such that the binder will cure.
The compositions of this invention can additionally be used to produce sandpaper and other abrasives by the production techniques customarily practiced with phenolic resin as binder. In the production of sandpapers, a layer of the binders of the invention, as base binders, is first of all applied (judiciously 10 g/m2) to an appropriate backing paper. The desired amount of particulate abrasive is scattered into the wet base binder. After initial drying a binder topcoat is applied (e.g. 5 g/m2). The paper coated in this way is then cured by heating at 170xc2x0 C. for 5 minutes.
The hardness and flexibility of the composition can be set at the desired level by way of the composition of polymer A1.
The compositions of the invention are also suitable as formaldehyde-free core sand binders for producing casting molds and cores for metal casting according to the conventional processes.